1. Field of the Invention
The present invention relates generally to the management of communication networks, and more specifically to synchronization of timing events between multiple management stations and a single agent station when the latter is sequentially executing processes requested by the management stations at the same time.
2. Description of the Related Art
In a communication network, SNMP (simple network management protocol) is the well known protocol for the management of the network elements, or agent stations such as hosts and routers under control of a management station, using attributes of management information base (MIB) in which management information of the network is stored. When the management station sequentially issues requests to an agent station to execute a number of processes, or "tasks", the agent station executes them serially. Since the time taken to execute a process varies for a number of reasons, the management station should know, in some way or other, the end timing of the execution of each process. To this end, a mechanism known as "synchronization" is used between management and agent functions.
According to one prior art method, an MIB attribute is defined to indicate the end timing of the execution of a process. After sending a process execution message to an agent station, the requesting management station confirms that the requested process has been executed by repeatedly polling the agent station with a confirmation message. If the execution is still in progress, the agent station returns an "in-progress" message, and replies with the end-timing MIB attribute if the process has been executed at the moment a confirmation message is received. However, since the management station is required to repeatedly interrogate the agent station to determine the current status of the process being executed, the network has to bear the burden of carrying increased traffic between management stations and an agent station.
According to another prior art as disclosed in Japanese Laid-Open Patent Specification Hei-8-274784, the agent station uses an MIB "trap" attribute as an end timing indication. No polling messages are sent from the management station after an initial request message has been sent to the agent station. However, if the trap message is lost, the management station has no way of ascertaining the end timing of the requested process.